1. Field of the Invention
This invention relates to a lawn mower, and more particularly to a lawn mower that includes a brake device and an electrical element unit, which are located respectively at two opposite sides of an assembly of an engine and a flywheel to thereby increase the safety and heat-dissipating effect of the lawn mower.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional lawn mower 1 is shown to include an oil tank unit 11, an engine 12, an electrical element unit 13, a flywheel 14, and a brake device 15. The electrical element unit 13 includes a carburetor (not shown), a plug (not shown), and an electrical circuit (not shown).
The flywheel 14 rotates in a clockwise direction, and has a side surface 141 that is formed with a plurality of ribs 142, which are arranged such that the flywheel 14 functions as a fan for creating an air current therearound. Thus, an airflow path is formed around the flywheel 14 so as to allow for dissipation of heat from the engine 12 and the electrical element unit 13 in an air-cooling manner.
The brake device 15 includes a fixed seat 151, a braking arm 152 disposed pivotally on the fixed seat 151 at a position under the flywheel 14, a braking shoe 153 secured to the braking arm 152, a coiled tension spring 154 interconnecting the braking arm 152 and the fixed seat 151, a braking line unit 155 connected to the braking arm 152, and a power switch 156 for controlling the supply of electricity to the engine 12.
Referring to FIG. 1, when it is desired to use the lawn mower 1, a lever (not shown) mounted on a driving handle (not shown) of the lawn mower 1 is actuated against the biasing action of the spring 154 so that the braking line unit 155 displaces the braking arm 152 toward the power switch 156. Thereafter, the power switch 156 is activated by the braking arm 152 so that electricity is supplied to the engine 12. At the same time, the flywheel 14 is released from the brake device 15 so that it can rotate and drive the engine 12, thereby allowing for the grass-cutting operation of the lawn mower 1.
Subsequently, referring to FIG. 2, when it is desired to stop the grass-cutting operation of the lawn mower 1, the lever (not shown) on the driving handle (not shown) is released. This causes the braking arm 152 to be pulled away from the power switch 156 by the spring 154, thereby interrupting the supply of power from the power switch 156 to the engine 12. Furthermore, the braking shoe 153 presses against the flywheel 14 so as to stop the flywheel 14 and the engine 12.
The aforesaid conventional lawn mower 1 suffers from the following disadvantages:    (1) Because the brake device 15 is disposed adjacent to an upper stream side of the electrical element unit 13 and the engine 12, a turbulent airflow will form between the brake device 15 and the electrical element unit 13, and between the brake device 15 and the engine 12. As a result, the heat-dissipating effect is reduced. Although the fixed seat 151 and an air-guiding unit 16 can guide air into the annular airflow path, such a configuration increases the manufacturing cost of the lawn mower 1.    (2) When the braking shoe 153 of the brake device 15 contacts the flywheel 14, some sparks are inevitably produced therebetween. If the sparks reach the electrical element unit 13, this poses an explosion or fire hazard.